Copper/ceramic bonded body, insulating circuit substrate, copper/ceramic bonded body production method, and insulating circuit substrate production method

ABSTRACT

A copper/ceramic bonded body includes: a copper member made of copper or a copper alloy; and a ceramic member made of a silicon nitride, wherein the copper member and the ceramic member are bonded to each other, a magnesium oxide layer is provided on a ceramic member side of a bonded interface between the copper member and the ceramic member, a Mg solid solution layer is provided between the magnesium oxide layer and the copper member and contains Mg in a state of a solid solution in a Cu primary phase, and a magnesium nitride phase is present on a magnesium oxide layer side of the Mg solid solution layer.

TECHNICAL FIELD

This invention relates to a copper/ceramic bonded body in which a coppermember made of copper or a copper alloy and a ceramic member made of asilicon nitride are bonded to each other, an insulating circuitsubstrate, a copper/ceramic bonded body production method, and aninsulating circuit substrate production method.

Priority is claimed on Japanese Patent Application No. 2018-159662,filed Aug. 28, 2018, the content of which is incorporated herein byreference.

BACKGROUND ART

A power module, an LED module, and a thermoelectric module have astructure in which a power semiconductor element, an LED element, or athermoelectric element is bonded to an insulating circuit substrate inwhich a circuit layer made of a conductive material is formed on onesurface of an insulating layer.

For example, a power semiconductor element for large power control,which is used to control wind power generation, an electric vehicle, ahybrid vehicle, and the like, generates a large amount of heat duringoperation. Therefore, as a substrate having such a power semiconductorelement mounted thereon, for example, an insulating circuit substrateprovided with a ceramic substrate made of a silicon nitride or the like,and a circuit layer formed by bonding a metal sheet having excellentconductivity to one surface of the ceramic substrate has been widelyused in the related art. As an insulating circuit substrate, one havinga metal layer formed by bonding a metal sheet to the other surface ofthe ceramic substrate is also provided.

For example, Patent Document 1 proposes an insulating circuit substratein which a first metal sheet and a second metal sheet respectivelyconstituting a circuit layer and a metal layer are formed of a coppersheet, and the copper sheets are directly bonded to a ceramic substrateby a DBC method. In the DBC method, the copper sheets and the ceramicsubstrate are bonded by generating a liquid phase at the interfacesbetween the copper sheets and the ceramic substrate using a eutecticreaction of copper and copper oxides.

In addition, Patent Document 2 proposes an insulating circuit substratein which a circuit layer and a metal layer are formed by bonding coppersheets to one surface and the other surface of a ceramic substrate. Inthe insulating circuit substrate, the copper sheets are disposed on onesurface and the other surface of the ceramic substrate with aAg—Cu—Ti-based brazing material interposed therebetween, and the coppersheets are bonded thereto by performing a heating treatment (so-calledactive metal brazing method). In the active metal brazing method, sincethe brazing material containing Ti as an active metal is used, thewettability between the molten brazing material and the ceramicsubstrate is improved, and the ceramic substrate and the copper sheetsare reliably bonded to each other.

Furthermore, Patent Document 3 proposes, as a brazing material forbonding, which is used when a copper sheet and a ceramic substrate arebonded to each other in a high-temperature nitrogen gas atmosphere, apaste containing a powder made of a Cu—Mg—Ti alloy. In Patent Document3, a configuration in which bonding is achieved by heating at 560° C. to800° C. in a nitrogen gas atmosphere is provided, and Mg in the Cu—Mg—Tialloy sublimates and does not remain at the bonded interface, whiletitanium nitride (TiN) is not substantially formed.

CITATION LIST Patent Document

[Patent Document 1]

Japanese Unexamined Patent Application, First Publication No. H04-162756

[Patent Document 2]

Japanese Patent No. 3211856

[Patent Document 3]

Japanese Patent No. 4375730

SUMMARY OF INVENTION Technical Problem

However, as disclosed in Patent Document 1, in a case where the ceramicsubstrate and the copper sheets are bonded according to the DBC method,the bonding temperature needs to be set to 1065° C. or higher (theeutectic point temperature of copper and copper oxides or higher), sothat there is concern that the ceramic substrate may deteriorate duringbonding. In addition, in a case where bonding is performed in a nitrogengas atmosphere or the like, there is a problem in that atmospheric gasremains at the bonded interface and partial discharge is likely tooccur.

As disclosed in Patent Document 2, in a case of bonding the ceramicsubstrate and the copper sheets according to the active metal brazingmethod, since the brazing material contains Ag and Ag is present at thebonded interface, migration easily occurs, and use for high-voltageapplications cannot be achieved. In addition, since the bondingtemperature is relatively as high as 900° C., there is concern that theceramic substrate may deteriorate. Furthermore, an intermetalliccompound phase containing a titanium nitride phase and Ti is generatedin the vicinity of the bonding surface of the ceramic substrate, andthere is concern that breaking may occur in the ceramic substrate duringhigh-temperature operation.

As disclosed in Patent Document 3, in a case where bonding is performedin a nitrogen gas atmosphere using a brazing material for bonding, whichis formed of the paste containing a powder made of a Cu—Mg—Tialloy, gasremains at the bonded interface, and there is a problem in that partialdischarge easily occurs. In addition, there is concern that organicmatter contained in the paste remains at the bonded interface and mayresult in insufficient bonding. Furthermore, an intermetallic compoundphase containing Ti is generated in the vicinity of the bonding surfaceof the ceramic substrate, and there is concern that breaking may occurin the ceramic substrate during high-temperature operation.

The present invention has been made in view of the above-describedcircumstances, and an objective thereof is to provide a copper/ceramicbonded body in which a copper member and a ceramic member are reliablybonded to each other, excellent migration resistance is achieved, andthe occurrence of ceramic breaking during high-temperature operation canbe suppressed, an insulating circuit substrate, a production method ofthe copper/ceramic bonded body, and a production method of theinsulating circuit substrate.

Solution to Problem

In order to solve these problems and achieve the above-mentioned object,a copper/ceramic bonded body of the present invention is acopper/ceramic bonded body, including: a copper member made of copper ora copper alloy; and a ceramic member made of a silicon nitride, wherein,the copper member and the ceramic member are bonded to each other, amagnesium oxide layer is provided on a ceramic member side of a bondedinterface between the copper member and the ceramic member, a Mg solidsolution layer is provided between the magnesium oxide layer and thecopper member and contains Mg in a state of a solid solution in a Cuprimary phase, and a magnesium nitride phase is present on a magnesiumoxide layer side of the Mg solid solution layer.

In the copper/ceramic bonded body having the configuration, themagnesium oxide layer is formed on the ceramic member side of the bondedinterface between the copper member and the ceramic member, the Mg solidsolution layer is formed between the magnesium oxide layer and thecopper member, and the magnesium nitride phase is present on themagnesium oxide layer side of the Mg solid solution layer. The magnesiumnitride phase is formed by the reaction between Mg disposed between theceramic member and the copper member and nitrogen in the ceramic member,and thus the ceramic member sufficiently reacts.

Therefore, the copper/ceramic bonded body in which the interfacialreaction sufficiently proceeds at the bonded interface between thecopper member and the ceramic member and the copper member and theceramic member are reliably bonded to each other can be obtained.

Since Ti, Zr, Nb, and Hf are not present at the bonded interface betweenthe Cu member and the ceramic member, a nitride phase of Ti, Zr, Nb, andHf and an intermetallic compound phase containing Ti, Zr, Nb, and Hf arenot generated, and breaking of the ceramic member can be suppressed evenduring high-temperature operation.

Since Ag is not present at the bonded interface between the Cu memberand the ceramic member, excellent migration resistance is also achieved.

In the copper/ceramic bonded body of the present invention, it ispreferable that in a region from a bonding surface of the ceramic memberto 50 μm toward a copper member side, an area ratio of an intermetalliccompound phase be 15% or less.

In this case, since the area ratio of the intermetallic compound phasein the region from the bonding surface of the ceramic member to 50 μmtoward the copper member side is 15% or less, there are not a largenumber of hard and brittle intermetallic compound phases in the vicinityof the bonding surface of the ceramic member, and it becomes possible toreliably suppress breaking of the ceramic member during high-temperatureoperation.

In the present invention, a nitride phase and an oxide phase areexcluded from the above-mentioned intermetallic compound phase.

An insulating circuit substrate of the present invention is aninsulating circuit substrate, including: a copper sheet made of copperor a copper alloy; and a ceramic substrate made of a silicon nitride,wherein, the copper sheet is bonded to a surface of the ceramicsubstrate, a magnesium oxide layer is provided on a ceramic substrateside of a bonded interface between the copper sheet and the ceramicsubstrate, a Mg solid solution layer is provided between the magnesiumoxide layer and the copper sheet and contains Mg in a state of a solidsolution in a Cu primary phase, and a magnesium nitride phase is presenton a magnesium oxide layer side of the Mg solid solution layer.

In the insulating circuit substrate having the configuration, the coppersheet and the ceramic substrate are reliably bonded to each other, andexcellent migration resistance is achieved, so that the insulatingcircuit substrate can be used with high reliability even underhigh-voltage conditions.

It is possible to suppress the occurrence of breaking in the ceramicsubstrate during high-temperature operation, and the insulating circuitsubstrate can be used with high reliability even under high-temperatureconditions.

In the insulating circuit substrate of the present invention, it ispreferable that in a region from a bonding surface of the ceramicsubstrate to 50 μm toward a copper sheet side, an area ratio of anintermetallic compound phase be 15% or less.

In this case, since the area ratio of the intermetallic compound phasein the region from the bonding surface of the ceramic substrate to 50 μmtoward the copper sheet side is 15% or less, there are not a largenumber of hard and brittle intermetallic compound phases in the vicinityof the bonding surface of the ceramic substrate, and it becomes possibleto reliably suppress breaking of the ceramic substrate duringhigh-temperature operation.

In the present invention, a nitride phase and an oxide phase areexcluded from the above-mentioned intermetallic compound phase.

A production method of a copper/ceramic bonded body of the presentinvention is a production method of a copper/ceramic bonded body forproducing the above-described copper/ceramic bonded body, the productionmethod including: a Mg-disposing step of disposing Mg between the coppermember and the ceramic member; a laminating step of laminating thecopper member and the ceramic member with Mg interposed therebetween;and a bonding step of performing a heating treatment on the coppermember and the ceramic member laminated with Mg interposed therebetweenin a state of being pressed in a laminating direction under a vacuumatmosphere to bond the copper member and the ceramic member to eachother, in which, in the Mg-disposing step, an amount of Mg is in a rangeof 0.17 mg/cm² or more and 3.48 mg/cm² or less.

According to the production method of a copper/ceramic bonded bodyhaving the above configuration, since Mg is disposed between the coppermember and the ceramic member and is subjected to the heating treatmentin a state of being pressed in the laminating direction under the vacuumatmosphere, no gas or no residue of organic matter remains at the bondedinterface.

In the Mg-disposing step, since the amount of Mg is in a range of 0.17mg/cm² or more and 3.48 mg/cm² or less, a liquid phase necessary for theinterfacial reaction can be sufficiently obtained. Therefore, it becomespossible to obtain the copper/ceramic bonded body in which the coppermember and the ceramic member are reliably bonded to each other.

Since Ti, Zr, Nb, and Hf are not used for bonding, a nitride phase ofTi, Zr, Nb, and Hf and an intermetallic compound phase containing Ti,Zr, Nb, and Hf are not present in the vicinity of the bonding surface ofthe ceramic member, and the copper/ceramic bonded body capable ofsuppressing breaking of the ceramic member during high-temperatureoperation can be obtained.

Since Ag is not used for bonding, the copper/ceramic bonded bodyexcellent in migration resistance can be obtained.

In the production method of a copper/ceramic bonded body of the presentinvention, it is preferable that, in the bonding step, a pressing loadbe in a range of 0.049 MPa or more and 3.4 MPa or less, and a heatingtemperature be in a range of 500° C. or higher and 850° C. or lower.

In this case, since the pressing load in the bonding step is in a rangeof 0.049 MPa or more and 3.4 MPa or less, the ceramic member, the coppermember, and Mg can be brought into close contact, so that theinterfacial reactions therebetween during heating can be promoted.

Since the heating temperature in the bonding step is equal to or higherthan 500° C., which is higher than the eutectic temperature of Cu andMg, a liquid phase can be sufficiently generated at the bondedinterface. On the other hand, since the heating temperature in thebonding step is 850° C. or lower, the excessive generation of the liquidphase can be suppressed. Furthermore, the thermal load on the ceramicmember is reduced, so that the deterioration of the ceramic member canbe suppressed. A production method of an insulating circuit substrate ofthe present invention is a production method of an insulating circuitsubstrate for producing the above-described insulating circuitsubstrate, the production method including: a Mg-disposing step ofdisposing Mg between the copper sheet and the ceramic substrate; alaminating step of laminating the copper sheet and the ceramic substratewith Mg interposed therebetween; and a bonding step of performing aheating treatment on the copper sheet and the ceramic substratelaminated with Mg interposed therebetween in a state of being pressed ina laminating direction under a vacuum atmosphere to bond the coppersheet and the ceramic substrate to each other, in which, in theMg-disposing step, an amount of Mg is in a range of 0.17 mg/cm² or moreand 3.48 mg/cm² or less.

According to the production method of the insulating circuit substratehaving the above configuration, since Mg is disposed between the coppersheet and the ceramic substrate and is subjected to the heatingtreatment in a state of being pressed in the laminating direction underthe vacuum atmosphere, no gas or no residue of organic matter remains atthe bonded interface.

In the Mg-disposing step, since the amount of Mg is in a range of 0.17mg/cm² or more and 3.48 mg/cm² or less, a liquid phase necessary for theinterfacial reaction can be sufficiently obtained. Therefore, it becomespossible to obtain the insulating circuit substrate in which the coppersheet and the ceramic substrate are reliably bonded to each other. Inaddition, since Ti, Zr, Nb, and Hf are not used for bonding, a nitridephase of Ti, Zr, Nb, and Hf and an intermetallic compound phasecontaining Ti, Zr, Nb, and Hf are not present in the vicinity of thebonding surface of the ceramic substrate, and the insulating circuitsubstrate capable of suppressing breaking of the ceramic substrateduring high-temperature operation can be obtained.

Since Ag is not used for bonding, the insulating circuit substrateexcellent in migration resistance can be obtained.

In the production method of the insulating circuit substrate of thepresent invention, it is preferable that, in the bonding step, apressing load be in a range of 0.049 MPa or more and 3.4 MPa or less,and a heating temperature be in a range of 500° C. or higher and 850° C.or lower.

In this case, since the pressing load in the bonding step is in a rangeof 0.049 MPa or more and 3.4 MPa or less, the ceramic substrate, thecopper sheet, and Mg can be brought into close contact, so that theinterfacial reactions therebetween during heating can be promoted.

Since the heating temperature in the bonding step is equal to or higherthan 500° C., which is higher than the eutectic temperature of Cu andMg, a liquid phase can be sufficiently generated at the bondedinterface. On the other hand, since the heating temperature in thebonding step is 850° C. or lower, the excessive generation of the liquidphase can be suppressed. Furthermore, the thermal load on the ceramicsubstrate is reduced, so that the deterioration of the ceramic substratecan be suppressed.

Advantageous Effects of Invention

According to the present invention, it becomes possible to provide acopper/ceramic bonded body in which a copper member and a ceramic memberare reliably bonded to each other, excellent migration resistance isachieved, and the occurrence of ceramic breaking during high-temperatureoperation can be suppressed, an insulating circuit substrate, aproduction method of the copper/ceramic bonded body, and a productionmethod of the insulating circuit substrate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic explanatory view of a power module using aninsulating circuit substrate (copper/ceramic bonded body) according toan embodiment of the present invention.

FIG. 2 is a schematic view of a bonded interface between a circuit layer(copper member) and a metal layer (copper member) and a ceramicsubstrate (ceramic member) of an insulating circuit substrate(copper/ceramic bonded body) according to the embodiment of the presentinvention.

FIG. 3 is a flowchart showing a production method of the insulatingcircuit substrate (copper/ceramic bonded body) according to theembodiment of the present invention.

FIG. 4 is an explanatory view showing the production method of theinsulating circuit substrate (copper/ceramic bonded body) according tothe embodiment of the present invention.

FIG. 5 is an observation result of a bonded interface between a coppersheet and a ceramic substrate in a copper/ceramic bonded body of Example5.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings.

A copper/ceramic bonded body according to the present embodiment is aninsulating circuit substrate 10 configured by bonding a ceramicsubstrate 11 which is a ceramic member to a copper sheet 22 (circuitlayer 12) and to a copper sheet 23 (metal layer 13), which are coppermembers.

FIG. 1 illustrates the insulating circuit substrate 10 according to theembodiment of the present invention and a power module 1 using theinsulating circuit substrate 10.

The power module 1 includes the insulating circuit substrate 10, asemiconductor element 3 bonded to one side (upper side in FIG. 1) of theinsulating circuit substrate 10 with a first solder layer 2 interposedtherebetween, and a heat sink 51 bonded to the other side (lower side inFIG. 1) of the insulating circuit substrate 10 with a second solderlayer 8 interposed therebetween.

The insulating circuit substrate 10 includes the ceramic substrate 11,the circuit layer 12 disposed on one surface (upper surface in FIG. 1)of the ceramic substrate 11, and the metal layer 13 disposed on theother surface (lower surface in FIG. 1) of the ceramic substrate 11.

The ceramic substrate 11 prevents the electrical connection between thecircuit layer 12 and the metal layer 13, and is made of a siliconnitride having high insulating properties, in the present embodiment.The thickness of the ceramic substrate 11 is set to be in a range of 0.2mm or more and 1.5 mm or less, and in the present embodiment, thethickness of the ceramic substrate 11 is preferably 0.32 mm

As illustrated in FIG. 4, the circuit layer 12 is formed by bonding thecopper sheet 22 made of copper or a copper alloy to one surface of theceramic substrate 11. In the present embodiment, a rolled sheet ofoxygen-free copper is used as the copper sheet 22 constituting thecircuit layer 12. A circuit pattern is formed on the circuit layer 12,and one surface thereof (upper surface in FIG. 1) becomes a mountingsurface on which the semiconductor element 3 is mounted. The thicknessof the circuit layer 12 is set to be in a range of 0.1 mm or more and1.0 mm or less, and in the present embodiment, the thickness of thecircuit layer 12 is preferably 0.6 mm.

As illustrated in FIG. 4, the metal layer 13 is formed by bonding thecopper sheet 23 made of copper or a copper alloy to the other surface ofthe ceramic substrate 11. In the present embodiment, a rolled sheet ofoxygen-free copper is used as the copper sheet 23 constituting the metallayer 13. The thickness of the metal layer 13 is set to be in a range of0.1 mm or more and 1.0 mm or less, and in the present embodiment, thethickness of the metal layer 13 is preferably 0.6 mm

The heat sink 51 is for cooling the above-mentioned insulating circuitsubstrate 10, and in the present embodiment, is a heat-dissipating sheetmade of a material having good thermal conductivity. In the presentembodiment, the heat sink 51 is made of copper or a copper alloyexcellent in thermal conductivity. The heat sink 51 and the metal layer13 of the insulating circuit substrate 10 are bonded to each other withthe second solder layer 8 interposed therebetween.

The ceramic substrate 11 and the circuit layer 12 (copper sheet 22), andthe ceramic substrate 11 and the metal layer 13 (copper sheet 23) arebonded to each other with a Mg film 25 interposed therebetween asillustrated in FIG. 4.

At the bonded interface between the ceramic substrate 11 and the circuitlayer 12 (copper sheet 22) and the bonded interface between the ceramicsubstrate 11 and the metal layer 13 (copper sheet 23), as illustrated inFIG. 2, a structure in which a magnesium oxide layer 31 formed on theceramic substrate 11 side of the bonded interface and a Mg solidsolution layer 32 in which Mg is in a state of a solid solution in a Cuprimary phase are laminated is provided.

The magnesium oxide layer 31 is made of, for example, MgO. The thicknessof the magnesium oxide layer 31 is in a range of 2 nm or more and 30 nmor less, and preferably in a range of 5 nm or more and 15 nm or less. Itis presumed that the magnesium oxide layer 31 is formed by the reactionof oxygen (O) of the oxide formed on the surface of the ceramicsubstrate 11 and magnesium (Mg) of the Mg film 25.

The amount of Mg in the Mg solid solution layer 32 is in a range of 0.01at % or more and 3 at % or less. The thickness of the Mg solid solutionlayer 32 is in a range of 0.1 μm or more and 150 μm or less, andpreferably in a range of 0.1 μm or more and 80 μm or less.

A magnesium nitride phase 35 is formed on the magnesium oxide layer 31side of the Mg solid solution layer 32. The magnesium nitride phase 35is made of, for example, Mg₃N₂ and has a needle-like structure. Themagnesium nitride phase 35 is partially formed in a region of the Mgsolid solution layer 32 on the magnesium oxide layer 31 side.

In the present embodiment, it is preferable that the area ratio of anintermetallic compound phase in a region from the bonding surface of theceramic substrate 11 to 50 μm toward the copper sheet 22 (circuit layer12) and the copper sheet 23 (metal layer 13) side be 15% or less.

As described above, when the area ratio of the intermetallic compoundphase at the bonded interface is suppressed, a Cu—Mg intermetalliccompound phase containing Cu and Mg may be dispersed inside the Mg solidsolution layer 32. Examples of the Cu—Mg intermetallic compound phaseinclude Cu₂Mg and CuMg₂.

Next, a production method of the insulating circuit substrate 10according to the present embodiment described above will be describedwith reference to FIGS. 3 and 4.

(Mg-Disposing Step S01)

As illustrated in FIG. 4, Mg is disposed between the copper sheet 22which is to become the circuit layer 12 and the ceramic substrate 11 andbetween the copper sheet 23 which is to become the metal layer 13 andthe ceramic substrate 11. In the present embodiment, the Mg film 25 isformed on the copper sheets 22 and 23 by vapor deposition of Mg.

In the Mg-disposing step S01, the amount of Mg to be disposed is in arange of 0.17 mg/cm² or more and 3.48 mg/cm² or less.

(Laminating Step S02)

Next, the copper sheet 22 and the ceramic substrate 11 are laminatedwith the Mg film 25 interposed therebetween, and the ceramic substrate11 and the copper sheet 23 are laminated with the Mg film 25 interposedtherebetween.

(Bonding Step S03)

Next, the copper sheet 22, the ceramic substrate 11, and the coppersheet 23 which are laminated are pressed in a laminating direction andare loaded into a vacuum furnace and heated such that the copper sheet22, the ceramic substrate 11, and the copper sheet 23 are bondedtogether.

The pressing load in the bonding step S03 is preferably in a range of0.049 MPa or more and 3.4 MPa or less.

The heating temperature in the bonding step S03 is preferably in a rangeof 500° C. or higher and 850° C. or lower.

The degree of vacuum in the bonding step S03 is preferably in a range of1×10⁻⁶ Pa or more and 5×10⁻² Pa or less.

The retention time at the heating temperature is preferably in a rangeof 5 minutes or longer and 180 minutes or shorter.

The temperature-lowering rate when the temperature is lowered from theheating temperature (bonding temperature) to 480° C. is not particularlylimited, but is preferably 20° C./min or less, and more preferably 10°C./min or less. In addition, the lower limit of the temperature-loweringrate is not particularly limited, but may be 2° C./min or more, 3°C./min or more, or 5° C./min or more.

As described above, the insulating circuit substrate 10 according to thepresent embodiment is produced by the Mg-disposing step S01, thelaminating step S02, and the bonding step S03.

(Heat Sink-Bonding Step S04)

Next, the heat sink 51 is bonded to the other surface side of the metallayer 13 of the insulating circuit substrate 10. The insulating circuitsubstrate 10 and the heat sink 51 are laminated with the solder materialinterposed therebetween and are loaded into a heating furnace such thatthe insulating circuit substrate 10 and the heat sink 51 are soldered toeach other with the second solder layer 8 interposed therebetween.

(Semiconductor Element-Bonding Step S05)

Next, the semiconductor element 3 is bonded to one surface of thecircuit layer 12 of the insulating circuit substrate10 by soldering.

The power module 1 illustrated in FIG. 1 is produced by the above steps.

According to the insulating circuit substrate 10 (copper/ceramic bondedbody) of the present embodiment configured as described above, thecopper sheet 22 (circuit layer 12) and the copper sheet 23 (metal layer13) made of oxygen-free copper and the ceramic substrate 11 made of asilicon nitride are bonded to each other with the Mg film 25 interposedtherebetween, the magnesium oxide layer 31 is formed on the ceramicsubstrate 11 side between the ceramic substrate 11 and the circuit layer12 (copper sheet 22) and between the ceramic substrate 11 and the metallayer 13 (copper sheet 22), the Mg solid solution layer 32 in which Mgis in a state of a solid solution in the Cu primary phase is laminated,and the magnesium nitride phase 35 is present on the magnesium oxidelayer 31 side of the Mg solid solution layer 32. The magnesium nitridephase 35 is formed by the reaction of Mg with nitrogen in the ceramicsubstrate 11, and thus the ceramic substrate 11 sufficiently reacts.

Therefore, an interfacial reaction proceeds sufficiently at the bondedinterfaces between the copper sheet 22 (circuit layer 12) and the coppersheet 23 (metal layer 13) and the ceramic substrate 11, so that theinsulating circuit substrate 10 (copper/ceramic bonded body) in whichthe copper sheet 22 (circuit layer 12) and the copper sheet 23 (metallayer 13) and the ceramic substrate 11 are reliably bonded can beobtained.

Since Ti, Zr, Nb, and Hf are not present at the bonded interfacesbetween the copper sheet 22 (circuit layer 12) and the copper sheet 23(metal layer 13) and the ceramic substrate 11, a nitride phase of Ti,Zr, Nb, and Hf and an intermetallic compound phase containing Ti, Zr,Nb, and Hf are not generated, and breaking of the ceramic substrate 11can be suppressed even during high-temperature operation. The totalamount of Ti, Zr, Nb, and Hf at the bonded interfaces between the coppersheet 22 (circuit layer 12) and the copper sheet 23 (metal layer 13) andthe ceramic substrate 11 is preferably 0.3 mass % or less, andpreferably 0.1 mass % or less.

Since Ag is not present at the bonded interfaces between the ceramicsubstrate 11 and the copper sheet 22 (circuit layer 12) and the coppersheet 23 (metal layer 13), excellent migration resistance is achieved.The amount of Ag at the bonded interfaces between the copper sheet 22(circuit layer 12) and the copper sheet 23 (metal layer 13) and theceramic substrate 11 is preferably 0.2 mass % or less, and morepreferably 0.1 mass % or less.

In the present embodiment, in a case where the area ratio of theintermetallic compound phase in the region from the bonding surface ofthe ceramic substrate 11 to 50 μm toward the copper sheet 22 (circuitlayer 12) and the copper sheet 23 (metal layer 13) side is 15% or less,there are not a large number of hard and brittle intermetallic compoundphases in the vicinity of the bonding surface of the ceramic substrate11, and it becomes possible to reliably suppress breaking of the ceramicsubstrate 11 during high-temperature operation.

The area ratio of the intermetallic compound phase in the region fromthe bonding surface of the ceramic substrate 11 to 50 μm toward thecopper sheet 22 (circuit layer 12) and the copper sheet 23 (metal layer13) side is preferably 10% or less, and more preferably 8% or less.

According to the production method of the insulating circuit substrate10 (copper/ceramic bonded body) of the present embodiment, since theMg-disposing step S01 of disposing Mg (the Mg film 25) between thecopper sheets 22 and 23 and the ceramic substrate 11, the laminatingstep S02 of laminating the copper sheets 22 and 23 and the ceramicsubstrate 11 with the Mg film 25 interposed therebetween, and thebonding step S03 of performing the heating treatment on the copper sheet22, the ceramic substrate 11, and the copper sheet 23 which arelaminated in a state of being pressed in the laminating direction undera vacuum atmosphere to bond the copper sheet 22, the ceramic substrate11, and the copper sheet 23 together are provided, no gas or no residueof organic matter remains at the bonded interface.

In the Mg-disposing step S01, since the amount of Mg is in a range of0.17 mg/cm² or more and 3.48 mg/cm² or less, a liquid phase necessaryfor the interfacial reaction can be sufficiently obtained. Therefore,the insulating circuit substrate 10 (copper/ceramic bonded body) inwhich the copper sheets 22 and 23 and the ceramic substrate 11 arereliably bonded can be obtained.

Since Ti, Zr, Nb, and Hf are not used for bonding, a nitride phase ofTi, Zr, Nb, and Hf and an intermetallic compound phase containing Ti,Zr, Nb, and Hf are not present in the vicinity of the bonding surface ofthe ceramic substrate 11, and the insulating circuit substrate 10(copper/ceramic bonded body) capable of suppressing breaking of theceramic substrate 11 during high-temperature operation can be obtained.

Since Ag is not used for bonding, the insulating circuit substrate 10(copper/ceramic bonded body) excellent in migration resistance can beobtained.

In a case where the amount of Mg is less than 0.17 mg/cm², the amount ofthe generated liquid phase is insufficient, and there is concern thatthe bonding rate may decrease. In a case where the amount of Mg exceeds3.48 mg/cm², the amount of the generated liquid phase becomes excessive,the liquid phase may leak from the bonded interface, and there isconcern that a bonded body having a predetermined shape may not beproduced. Furthermore, the amount of the generated liquid phase becomesexcessive, the Cu—Mg intermetallic compound phase may be excessivelygenerated, and there is concern that breaking may occur in the ceramicsubstrate 11.

From the above description, in the present embodiment, the amount of Mgis in a range of 0.17 mg/cm² or more and 3.48 mg/cm² or less.

The lower limit of the amount of Mg is preferably 0.24 mg/cm² or more,and more preferably 0.32 mg/cm² or more. On the other hand, the upperlimit of the amount of Mg is preferably 2.38 mg/cm² or less, and morepreferably 1.58 mg/cm² or less.

In the present embodiment, since the pressing load in the bonding stepS03 is 0.049 MPa or more, the ceramic substrate 11, the copper sheets 22and 23, and the Mg film 25 can be brought into close contact, so thatthe interfacial reactions therebetween during heating can be promoted.Since the pressing load in the bonding step S03 is 3.4 MPa or less,breaking and the like in the ceramic substrate 11 in the bonding stepS03 can be suppressed.

The lower limit of the pressing load in the bonding step S03 ispreferably 0.098 MPa or more, and more preferably 0.294 MPa or more. Onthe other hand, the upper limit of the pressing load in the bonding stepS03 is preferably 1.96 MPa or less, and more preferably 0.98 MPa orless.

In the present embodiment, since the heating temperature in the bondingstep S03 is equal to or higher than 500° C., which is higher than theeutectic temperature of Cu and Mg, a liquid phase can be sufficientlygenerated at the bonded interface. On the other hand, since the heatingtemperature in the bonding step S03 is 850° C. or lower, the excessivegeneration of the liquid phase can be suppressed. Furthermore, thethermal load on the ceramic substrate 11 is reduced, so that thedeterioration of the ceramic substrate 11 can be suppressed.

The lower limit of the heating temperature in the bonding step S03 ispreferably 600° C. or higher, and more preferably 680° C. or higher. Onthe other hand, the upper limit of the heating temperature in thebonding step S03 is preferably 800° C. or lower, and more preferably760° C. or lower.

In the present embodiment, in a case where the degree of vacuum in thebonding step S03 is in a range of 1×10⁻⁶ Pa or more and 5×10⁻² Pa orless, the oxidation of the Mg film 25 can be suppressed, and it becomespossible to reliably bond the ceramic substrate 11 and the copper sheets22 and 23.

The lower limit of the degree of vacuum in the bonding step S03 ispreferably 1×10⁻⁴ Pa or more, and more preferably 1×10⁻³ Pa or more. Onthe other hand, the upper limit of the degree of vacuum in the bondingstep S03 is preferably 1×10⁻² Pa or less, and more preferably 5×10⁻³ Paor less.

In the present embodiment, in a case where the retention time at theheating temperature in the bonding step S03 is in a range of 5 minutesor longer and 180 minutes or shorter, a liquid phase can be sufficientlyformed, and it becomes possible to reliably bond the ceramic substrate11 and the copper sheets 22 and 23.

The lower limit of the retention time at the heating temperature in thebonding step S03 is preferably 10 minutes or longer, and more preferably30 minutes or longer. On the other hand, the upper limit of theretention time at the heating temperature in the bonding step S03 ispreferably 150 minutes or shorter, and more preferably 120 minutes orshorter.

While the embodiments of the present invention have been describedabove, the present invention is not limited thereto and can be modifiedas appropriate without departing from the technical spirit of theinvention.

For example, although the copper sheet which constitutes the circuitlayer or the metal layer is described as the rolled sheet of oxygen-freecopper, the copper sheet is not limited thereto, and may also be made ofanother kind of copper or copper alloy.

In the present embodiment, although the circuit layer and the metallayer are described as being constituted by the copper sheets, thecircuit layer and the metal layer are not limited thereto. As long as atleast one of the circuit layer and the metal layer is constituted by acopper sheet, the other may be constituted by another metal sheet suchas an aluminum sheet.

In the present embodiment, although it is described in the Mg-disposingstep that the Mg film is formed by vapor deposition, the Mg film is notlimited thereto, and the Mg film may be formed by another method, or aMg foil may be disposed. Alternatively, a clad material of Cu and Mg maybe disposed.

A Mg paste and a Cu—Mg paste may be applied. In addition, a Cu paste anda Mg paste may be laminated and disposed. At this time, the Mg paste maybe disposed on either the copper sheet side or the ceramic substrateside. In addition, MgH₂ may be disposed as Mg.

Although the heat sink is exemplified by the heat-dissipating sheet, theheat sink is not limited thereto, and there is no particular limitationon the structure of the heat sink. For example, one having a passagethrough which a refrigerant flows or one having a cooling fin may beused. In addition, as the heat sink, a composite material (for example,AISiC) containing aluminum or an aluminum alloy can also be used.

Furthermore, a buffer layer made of aluminum or an aluminum alloy or acomposite material containing aluminum (for example, AISiC) may beprovided between the top sheet part or heat-dissipating sheet of theheat sink and the metal layer.

In the present embodiment, configuring the power module by mounting thepower semiconductor element on the circuit layer of the insulatingcircuit substrate has been described, but the present embodiment is notlimited thereto. For example, an LED module may be configured bymounting an LED element on the insulating circuit substrate, or athermoelectric module may be configured by mounting a thermoelectricelement on the circuit layer of the insulating circuit substrate.

EXAMPLES Examples 1 to 12

A confirmatory experiment performed to confirm the effectiveness of thepresent invention will be described.

A copper/ceramic bonded body was formed by laminating copper sheets(oxygen-free copper, 37 mm square, thickness 1.2 mm) in which Mg wasdisposed as shown in Table 1, on both surfaces of a 40 mm square ceramicsubstrate made of a silicon nitride and bonding the laminated sheetsunder bonding conditions shown in Table 1. The thickness of the ceramicsubstrate was 0.32 mm. In addition, the degree of vacuum of the vacuumfurnace at the time of bonding was 5×10⁻³ Pa.

In a related art example, an active brazing material of Ag-28 mass %Cu-6 mass % Ti was disposed between the ceramic substrate and the coppersheet so that the amount of Ag was 5.2 mg/cm².

In addition, when the temperature in the bonding step S03 was loweredfrom the bonding temperature (“Temperature (° C.)” in Table 1) to 480°C., the temperature-lowering rate was controlled to be a rate of 5°C./min. The temperature-lowering rate is controlled by the partialpressure of a gas during gas cooling (whether or not circulation isperformed by a cooling fan).

Regarding the copper/ceramic bonded bodies obtained as described above,the bonded interface was observed, and a Mg solid solution layer, aCu—Mg intermetallic compound phase, a magnesium nitride phase werechecked. In addition, the initial bonding rate of the copper/ceramicbonded body, breaking of the ceramic substrate after thermal cycles, andmigration properties were evaluated as follows.

(Mg Solid Solution Layer)

Regarding the bonded interface between the copper sheet and the ceramicsubstrate, a region (400 μm×600 μm) including the bonded interface wasobserved under the conditions of a magnification of 2,000 times and anaccelerating voltage of 15 kV using an EPMA apparatus (JXA-8539Fmanufactured by JEOL Ltd.), quantitative analysis was performed on arange of 10 points or more and 20 points or less depending on thethickness of the copper sheet at intervals of 10 μm from the surface ofthe ceramic substrate toward the copper sheet side, and a region havinga Mg concentration of 0.01 at % or more was regarded as a Mg solidsolution layer.

(Area Ratio of Cu—Mg Intermetallic Compound Phase)

Regarding the bonded interface between the copper sheet and the ceramicsubstrate, an element map of Mg of the region (400 μm×600 μm ) includingthe bonded interface was acquired under the conditions of amagnification of 2,000 times and an accelerating voltage of 15 kV usingan electron micro analyzer (JXA-8539F manufactured by JEOL Ltd.), and aregion satisfying that the Cu concentration as a five-point average ofquantitative analysis in the region where the presence of Mg wasconfirmed was 5 at % or more and the Mg concentration was 30 at % ormore and 70 at % or less was regarded as a Cu—Mg intermetallic compoundphase.

Then, the area ratio (%) of the intermetallic compound phase in theregion from the bonding surface of the ceramic substrate to 50 μm towardthe copper sheet side was calculated.

(Magnesium Nitride Phase)

The bonded interface between the copper sheet and the ceramic substratewas observed using a transmission electron microscope (Titan ChemiSTEMmanufactured by FEI Company) at an accelerating voltage of 200 kV and amagnification of 40,000 times, and a case where a region where Mg and Ncoexisted was present and the Mg concentration in the region was 50 at %or more and 70 at % or less was evaluated as a magnesium nitride layer“present”.

(Initial Bonding Rate)

The bonding rate between the copper sheet and the ceramic substrate wasobtained using the following equation using an ultrasonic flaw detector(FineSAT200 manufactured by Hitachi Power Solutions Co., Ltd.). Theinitial bonding area was the area to be bonded before bonding, that is,the area of the bonding surface of the copper sheet. In theultrasonic-detected image, peeling was indicated by a white portion inthe bonding part, and thus the area of the white portion was regarded asa peeled area.

(Initial bonding rate)={(initial bonding area)−(peeled area)}/(initialbonding area)

(Breaking in Ceramic Substrate)

Using a thermal shock tester (TSA-72ES manufactured by ESPEC Corp.),1000 cycles, where one cycle is 10 minutes at −50° C. and 10 minutes at150° C., were performed in a gas phase.

The presence or absence of breaking in the ceramic substrate afterapplying the above-mentioned thermal cycles was evaluated.

(Migration)

The electric resistance between circuit patterns was measured afterbeing left for 2,000 hours under the conditions of a distance betweenthe circuit patterns separated by insulation in a circuit layer of 0.5mm, a temperature of 85° C., a humidity of 85%RH, and a voltage ofDC50V. A case where the resistance value was 1×10⁶ Ω or less wasdetermined as a short-circuit (migration had occurred), and themigration was evaluated as “B”. After being left for 2,000 hours underthe same conditions as above, the electric resistance between thecircuit patterns was measured. A case where the resistance value wasgreater than 1×10⁶ Ω was determined as the absence of migration, and themigration was evaluated as “A”.

The evaluation results are shown in Table 2. In addition, theobservation results of Example 5 are shown in FIG. 5.

TABLE 1 Mg-disposing step Bonding step Amount of Mg Load TemperatureTime mg/cm² MPa ° C. min Example 1 1.58 0.98 600 150 Example 2 0.32 1.96760 90 Example 3 0.29 1.96 720 5 Example 4 0.17 0.049 500 10 Example 50.24 3.4 850 180 Example 6 2.53 0.98 830 150 Example 7 0.79 1.96 800 90Example 8 1.27 0.294 740 60 Example 9 3.48 0.294 850 180 Example 10 2.381.96 680 30 Example 11 1.43 1.96 650 120 Example 12 2.22 0.049 820 90Comparative 0.11 3.4 850 180 Example 1 Comparative 6.34 0.049 740 90Example 2 Related Art (Active brazing 0.049 820 90 Example material)

29

TABLE 2 Observation result of bonded interface Area ratio of Cu—MgPresence or Magnesium Mg solid intermetallic Initial absence of nitridesolution compound phase bonding ceramic phase layer (%) rate % breakingMigration Example 1 Present Present 10.6 98.3 Absent A Example 2 PresentPresent 0.9 94.7 Absent A Example 3 Present Present 3.2 93.5 Absent AExample 4 Present Present 4.2 91.3 Absent A Example 5 Present Present0.0 97.2 Absent A Example 6 Present Present 5.8 99.4 Absent A Example 7Present Present 2.4 96.1 Absent A Example 8 Present Present 4.7 99.0Absent A Example 9 Present Present 6.1 98.4 Absent A Example 10 PresentPresent 9.5 97.1 Absent A Example 11 Present Present 8.8 98.2 Absent AExample 12 Present Present 5.8 96.9 Absent A Comparative Bonded body wasnot formed, and evaluation was stopped Example 1 Comparative Bonded bodywas not formed, and evaluation was stopped Example 2 Related Art — — —98.0 Present B Example

In Comparative Example 1 in which the amount of Mg was 0.11 mg/cm² inthe Mg-disposing step, which was smaller than the range of the presentinvention, since the liquid phase was insufficient at the time ofbonding, a bonded body could not be formed. Therefore, the subsequentevaluation was stopped.

In Comparative Example 2 in which the amount of Mg was 6.34 mg/cm² inthe Mg-disposing step, which was greater than the range of the presentinvention, since the liquid phase was excessively generated at the timeof bonding, the liquid phase leaked from the bonded interface and abonded body having a predetermined shape could not be produced.Therefore, the subsequent evaluation was stopped.

In the related art example in which a ceramic substrate and a coppersheet were bonded to each other using a Ag—Cu—Ti brazing material,evaluation of migration was determined as “B”. It is presumed that thisis because Ag was present at the bonded interface.

Contrary to this, in Examples 1 to 12, the initial bonding rate washigh, and no breaking was confirmed in the ceramic substrate. Also,migration was good.

Furthermore, as shown in FIG. 5, as a result of observing the bondedinterface, the Mg solid solution layer was observed. In addition, amagnesium oxide layer was observed, and a magnesium nitride phase wasconfirmed on the magnesium oxide layer side of the Mg solid solutionlayer.

Examples 21 to 32

Copper/ceramic bonded bodies were produced in the same manner as thecopper/ceramic bonded bodies produced in Examples 1 to 12, and regardingthe obtained copper/ceramic bonded bodies, the area ratio of Cu₂Mg andan ultrasonic bonded interface were evaluated as follows.

The evaluations of the area ratios of the Mg solid solution layer andthe Cu—Mg intermetallic compound phase, and the initial bonding rate ofthe copper/ceramic bonded body were performed in the same manner as inthe evaluations performed in Examples 1 to 12.

(Temperature-Lowering Rate)

In the bonding step S03, when the temperature was lowered from thebonding temperature (“Temperature (° C.)” in Table 3) to 480° C., thetemperature-lowering rate was controlled to be the rate shown in Table3.

(Area Ratio of Cu₂Mg)

In the Cu—Mg intermetallic compound phase, the area ratio (%) of Cu2Mgwas defined and calculated by the following calculation formula.

Area ratio (%) of Cu₂Mg=area of Cu₂Mg/(area of Cu₂Mg+area of CuMg₂)×100

“Area of Cu₂Mg” was a region in which the Mg concentration was 30 at %or more and less than 60 at % , and “area of CuMg₂” was a region inwhich the Mg concentration was 60 at % or more and less than 70 at %.

(Ultrasonic Bonding)

Regarding the obtained copper/ceramic bonded bodies, using an ultrasonicmetal bonder (60C-904 manufactured by Ultrasonic Engineering Co., Ltd.),a copper terminal (10 mm×5 mm×1.5 mm thick) was ultrasonically bondedunder the condition of a collapse amount of 0.5 mm.

After bonding, the bonded interface between the copper sheet and theceramic substrate was inspected using the ultrasonic flaw detector(FineSAT200 manufactured by Hitachi Power Solutions Co., Ltd.). Those inwhich peeling was observed were evaluated as “B”, and those in whichneither was confirmed were evaluated as “A”. The evaluation results areshown in Table 3.

TABLE 3 Observation result of bonded interface Mg- Bonding step Arearatio disposing Temper- of Cu—Mg step ature- Magne- inter- Area AmountTemper- lowering sium Mg solid metallic ratio of Initial Ultra- of MgLoad ature Time rate nitride solution compound Cu₂Mg bonding sonic(mg/cm²) (MPa) (° C.) (min) (° C./min) phase layer phase (%) (%) rate(%) bonding Example 21 1.58 0.98 600 150 5 Present Present 11.4 92.498.3 A Example 22 1.58 0.98 600 150 8 Present Present 10.6 93.5 97.3 AExample 23 1.58 0.98 600 150 16 Present Present 11.1 74.7 98.6 A Example24 1.58 0.98 600 150 24 Present Present 10.3 63.4 99.0 B Example 25 2.381.96 680 30 2 Present Present 10.5 99.4 98.8 A Example 26 2.38 1.96 68030 5 Present Present 9.5 96.2 97.1 A Example 27 2.38 1.96 680 30 10Present Present 8.7 86.7 97.0 A Example 28 2.38 1.96 680 30 30 PresentPresent 10.1 53.1 97.2 B Example 29 1.43 1.96 650 120 3 Present Present8.8 97.9 98.1 A Example 30 1.43 1.96 650 120 5 Present Present 8.8 99.098.2 A Example 31 1.43 1.96 650 120 20 Present Present 9.3 70.2 97.5 AExample 32 1.43 1.96 650 120 30 Present Present 8.9 56.3 98.6 B

The value of the area ratio of Cu2Mg and the bonding properties ofultrasonic bonding changed depending on the temperature-lowering rateafter the bonding step S03.

From the results shown in Table 3, it became clear that thetemperature-lowering rate is preferably 20° C./min, and more preferably10° C./min.

From the results shown in Table 3, it became clear that in the Cu—Mgintermetallic compound phase, the area ratio of Cu2Mg is preferably 70%or more, more preferably 85% or more, and even more preferably 90% ormore.

From the above description, according to the Examples, it was confirmedthat it is possible to provide a copper/ceramic bonded body (insulatingcircuit substrate) in which a copper member and a ceramic member arereliably bonded to each other, excellent migration resistance isachieved, and the occurrence of ceramic breaking during high-temperatureoperation can be suppressed.

In addition, according to the Examples, it was confirmed that it ispossible to provide a copper/ceramic bonded body (insulating circuitsubstrate) in which a copper member and a ceramic member are reliablybonded to each other by controlling a temperature-lowering rate from abonding temperature to 480° C., and excellent ultrasonic bondingproperties were achieved.

Industrial Applicability

According to the present invention, it becomes possible to provide acopper/ceramic bonded body in which a copper member and a ceramic memberare reliably bonded to each other, excellent migration resistance isachieved, and the occurrence of ceramic breaking during high-temperatureoperation can be suppressed, an insulating circuit substrate, aproduction method of the copper/ceramic bonded body, and a productionmethod of the insulating circuit substrate.

REFERENCE SIGNS LIST

10 Insulating circuit substrate

11 Ceramic substrate

12 Circuit layer

13 Metal layer

22, 23 Copper sheet

31 Magnesium oxide layer

32 Mg solid solution layer

35 Magnesium nitride phase

1. A copper/ceramic bonded body, comprising: a copper member made ofcopper or a copper alloy; and a ceramic member made of a siliconnitride, wherein, the copper member and the ceramic member are bonded toeach other; a magnesium oxide layer is provided on a ceramic member sideof a bonded interface between the copper member and the ceramic member,a Mg solid solution layer is provided between the magnesium oxide layerand the copper member and contains Mg in a state of a solid solution ina Cu primary phase, and a magnesium nitride phase is present on amagnesium oxide layer side of the Mg solid solution layer.
 2. Thecopper/ceramic bonded body according to claim 1, wherein, in a regionfrom a bonding surface of the ceramic member to 50 μm toward a coppermember side, an area ratio of an intermetallic compound phase is 15% orless.
 3. An insulating circuit substrate, comprising: a copper sheetmade of copper or a copper alloy; and a ceramic substrate made of asilicon nitride, wherein, the copper sheet is bonded to a surface of theceramic substrate, a magnesium oxide layer is provided on a ceramicsubstrate side of a bonded interface between the copper sheet and theceramic substrate, a Mg solid solution layer is provided between themagnesium oxide layer and the copper sheet and contains Mg in a state ofa solid solution in a Cu primary phase, and a magnesium nitride phase ispresent on a magnesium oxide layer side of the Mg solid solution layer.4. The insulating circuit substrate according to claim 3, wherein, in aregion from a bonding surface of the ceramic substrate to 50 μm toward acopper sheet side, an area ratio of an intermetallic compound phase is15% or less.
 5. A production method of a copper/ceramic bonded body, forproducing the copper/ceramic bonded body according to claim 1, theproduction method comprising: a Mg-disposing step of disposing Mgbetween the copper member and the ceramic member; a laminating step oflaminating the copper member and the ceramic member with Mg interposedtherebetween; and a bonding step of performing a heating treatment onthe copper member and the ceramic member laminated with Mg interposedtherebetween in a state of being pressed in a laminating direction undera vacuum atmosphere to bond the copper member and the ceramic member toeach other, wherein, in the Mg-disposing step, an amount of Mg is in arange of 0.17 mg/cm² or more and 3.48 mg/cm² or less.
 6. The productionmethod of a copper/ceramic bonded body according to claim 5, wherein, inthe bonding step, a pressing load is in a range of 0.049 MPa or more and3.4 MPa or less, and a heating temperature is in a range of 500° C. orhigher and 850° C. or lower.
 7. A production method of the insulatingcircuit substrate according to claim 3, the production methodcomprising: a Mg-disposing step of disposing Mg between the copper sheetand the ceramic substrate; a laminating step of laminating the coppersheet and the ceramic substrate with Mg interposed therebetween; and abonding step of performing a heating treatment on the copper sheet andthe ceramic substrate laminated with Mg interposed therebetween in astate of being pressed in a laminating direction under a vacuumatmosphere to bond the copper sheet and the ceramic substrate to eachother, wherein, in the Mg-disposing step, an amount of Mg is in a rangeof 0.17 mg/cm² or more and 3.48 mg/cm² or less.
 8. The production methodof the insulating circuit substrate according to claim 7, wherein, inthe bonding step, a pressing load is in a range of 0.049 MPa or more and3.4 MPa or less, and a heating temperature is in a range of 500° C. orhigher and 850° C. or lower.